The subject of the present invention is a connector provided with a switching device of the kind described in the preamble portion of patent claim 1. Such a connector is known for example from U.S. Pat. No. 5,741,146.
The invention can be used especially for switching between two aerial channels dedicated, for example, to mobile telephony. In this field, this type of connector is designed to allow switching, especially in a radio frequency range going from a few hundred MHz to a few GHz, from an internal aerial of a mobile telephone, used in portable mode, to an aerial external to the mobile telephone, for example that of a vehicle, to which external aerial the mobile telephone would be connected as required. The invention finds its justification more particularly in the mounting of such connectors on a printed circuit.
U.S. Pat. No. 4,633,048 describes a jack with a switch having a movable contact in a structure in which the contact is driven and separated from a fixed contact when the plug is inserted thereinto and the movable contact is brought into contact electrically with the plug. The housing of the jack has a longitudinal extension, which does not allow certain applications where a compact structure is obligatory.
U.S. Pat. No. 5,741,146 discloses a connector provided with a device for switching between two channels, this device including a first, fixed blade connected to a first channel and a second resilient switching blade exerting a contact pressure either on the first, fixed blade or on a pin of another connector, this pin being connected to a second channel and being inserted as required into the connector and wherein the second end of each blade is bent over in a same contact plane so that it is parallel to a contact surface on a printed circuit board and further comprising a hollow body inside which said device for switching is mounted, the second ends of the contact blades are supported by pins that give them a poor alignment with respect to a reference plane. The object of the invention is to propose a switch connector having a simple structure, compatible with the requirements of miniaturization, easy to mount on a printed-circuit board with an improved and more accurate alignment of the second ends of the blades in a predetermined contact plane of a printed circuit board and allowing effective and noise-free transmission within a radio frequency range.
A connector of this type consists of a hollow body inside which the aerial switching is carried out by means of two blades. The blades, when they are in electrical contact with each other, ensure connection between a transmitter/receiver and the internal aerial or, when they are separated (when introducing a coaxial plug of another connector into the hollow body), ensure connection between the transmitter/receiver and an external aerial. The advantage of the invention lies in the improvement and the simplification of these connections.
The coaxial pin of the other connector in most cases has a circular cylindrical shape. The contact thus formed between this pin and the resilient switching blade of the connector is a quasi-point contact in the case of a non-deformable material. In reality, the materials are not completely non-deformable, especially the switching blade which is resilient. Thus, a so-called quasi-point contact is in fact a contact in which the contact region is not a point but an area. However, in practice, given the dimensions of the components making the contact with respect to this contact area, it may be assumed that this area is sufficiently small to be regarded as a point. In fact, this contact area extends circularly at most over a quarter of the cross section of the circular cylindrical pin. This will constitute hereafter the definition of a point contact.
This type of connector has problems. With the requirements of miniaturization, the point contact area obtained is, for a pin less than 0.7 mm in diameter, less than 0.1 mm2. This type of contact is therefore not sufficiently effective to ensure that information is correctly transmitted or received. The effectiveness is in fact directly related to the quality of the electrical linkage produced. In addition, the contact resistance increases as the contact area decreases. A problem arises, especially when transmitting signals via the external aerial. This is because a signal emitted by this aerial may, in the case of mobile telephony, have a maximum peak power of up to eight watts. Thus, the transmission of such a signal through a point contact has the effect of causing the point of contact to heat up. This heat-up increases the rate of degradation of the contact, especially by oxidation. This causes accelerated reduction in the quality of the transmission of the signal from the transmitter to the external aerial.
Furthermore, another problem arises with regard to fastening such a connector to a printed circuit. The use of screws for doing this fastening is illusory,since the screws necessary would be too small to allow them to be easily handled by an operator. This therefore makes the fastening of these connectors to a printed circuit complicated, and therefore goes counter to the concern, expressed above, for simplicity.
A further object of the present invention is to remedy the problems mentioned by proposing a connector which includes a resilient switching blade allowing surface contact with a pin of another connector. The purpose of this surface contact is to improve the transmission qualities of a signal from a transmitter to an aerial or of a signal from, an aerial to a receiver, while at the same time satisfying the miniaturization requirements. Thus, with this surface contact, the overall contact area is increased. By increasing the overall contact area, the contact resistance is reduced.
A further object of the present invention is to provide an effective solution to these coplanarity problems by using a novel technique or technology for designing the present miniature coaxial switch or changeover-switch connector. This technique concerns the metallization of plastics, more particularly known by the name MID (Moulded Interconnection Device).
The invention thus aims to provide a miniature switch connector intended to be surface-mounted on a printed-circuit board, which includes a hollow plastic body comprising, at one of its ends, an opening intended to receive a connection plug which engages, during its insertion into this opening, with a resilient contact blade in order to separate the latter from a conductive surface, this contact blade and this conductive surface being connected to two conductive areas located at that end of the hollow body which is on the opposite side from the said opening.
According to the invention, this switch connector is characterized in that the said conductive surface consists of a metallized layer applied to part of the internal surface of the hollow plastic body. Further, the two conductive areas are coplanar and consist of two metallized layers applied to the external plane face of the hollow body which is on the opposite side from the said opening.
Given that the two metallized layers which act as output pads or terminals of the connector are applied to a plane face of the hollow body, the coplanarity of the two metallized surfaces is thus guaranteed, which in turn allows the connector to be surface-mounted extremely well.
In the invention, in practice two contact regions are made on the pin of the other connector. A first contact region defines a point contact, as described above, the second contact region being offset to the periphery of the pin. This has the effect of reducing the overall contact resistance due to connection between the resilient switching blade and the pin of the other connector. It will be seen that an elastic reaction, ensuring the first contact, is obtained by the elasticity of the resilient blade in its anchoring. The second contact is obtained by the elasticity of a side arm of this resilient blade. In order to ensure simple and effective fastening of this connector to a printed circuit, it is mounted using a surface mounting technique. Nevertheless, the elasticity of the arm allows firm contact to be made even if the anchoring is relatively fragile, especially when it results from surface mounting with a single soldered joint.
The invention therefore also relates to a connector provided with a device for switching between two channels, this device including a first, fixed blade connected to a first channel and a second, resilient switching blade exerting a contact pressure either on the first, fixed blade or on a pin of another connector, this pin being connected to a second channel and being inserted as required into the connector, characterized in that the pin comes into contact with the second blade at two points which are offset one with respect to the other on the periphery of the pin.
Preferably, a second contact of the second blade with this pin is obtained because this second blade includes a curved side arm which projects so as to be perpendicular to one surface of this second blade and a curvature of which is made along this projection.